Took Plan B, one day period?

So on August 14th, I had sex and my partner's condom slipped off while he was pulling out and some of his ejaculate landed on (not in) my vagina. I took Plan B within the hour and I felt no symptoms for two weeks until today, about the 2 days after my period was intended to come. It felt like my period came as I had bad cramping and there was heavy blood flow, but the flow seems to be tapering off.I've dug around Google, but I find nothing about my situation. So I have 2 questions1. Does the heavy bleeding mean I'm out of the woods?2. Was this my period or should I be prepped for another wave in a few days?